The present invention relates to a disc changer for playing a plurality of discs in a sequence.
Some modern disc playback devices such as compact disc players incorporate disc changers for automatically playing a plurality of discs in a sequence.
One known disc changer will be described below with reference to FIGS. 8 and 9 of the accompanying drawings.
As shown in FIG. 8, a disc changer includes a circular tray 1 mounted on a base 2 for rotation in the directions indicated by the arrow b. The base 2 is slidably disposed in a housing 3, and can be moved into the housing 3 in the direction indicated by the arrow c. In FIG. 8, the base 2 is shown as being moved out of the housing 3. With the base 2 thus projecting from the housing 3, a plurality of discs 5 such as compact discs can be placed in respective disc recesses 1a defined in the upper surface of the tray 1. The housing 3 has a front panel 4 which supports control buttons 6 and a display unit 7.
FIG. 9 shows a drive system incorporated in the disc changer. A base sliding mechanism 9 is fixedly mounted on a chassis 8 which is fixedly mounted in the housing 3. The base sliding mechanism 9 has a drive motor 9a and a speed reducer gear train including a gear 9b which meshes with a rack 2a fixed to the lower surface of the base 2. When the drive motor 9a is energized, the gear 9b is rotated through the speed reducer gear train to move the base 2 in the direction indicated by the arrow c. A pickup lifting/lowering mechanism 10 is fixed to the lower surface of the base 2. The pickup lifting/lowering mechanism 10 includes a drive motor 10a, a lifting/lowering cam 10b, and a pickup 13 which includes a turntable 13a and an optical system 13b. Rotation produced by the drive motor 10a is converted into vertical movement by the lifting/lowering cam 10b to lift or lower the pickup 13 about a shaft 10c in one of the directions indicated by the arrows d. While a disc is being played back, the pickup 13 is held in an upper position. While the tray 1 is rotating about its shaft 1c, the pickup 13 is held in a lower position. A tray rotating mechanism 11 is mounted on the upper surface of the base 2. The tray rotating mechanism 11 comprises a drive motor 11a and a gear train including a gear 11b held in mesh with an external gear 1b on and around the outer circumference of the tray 1. When the drive motor 11a is energized, the tray 1 is rotated about the shaft 1c in the direction indicated by the arrow b. When a desired one of the discs 5 has reached a playback position 12a, the drive motor 11a is de-energized to stop the tray 1.
The conventional disc changer thus constructed operates as follows:
With the base 2 projecting out of the housing 3, a plurality of discs 5 are mounted respectively in the disc recesses 1a of the tray 1. One of the control buttons 6 is pushed to produce a command for sliding movement of the base 2. The drive motor 9a is energized to cause the gear 9b and the rack 2a to move the base 2 back into the housing 3 until the front face of the base 2 lies flush with the front face of the front panel 4. Then, the drive motor 11a is energized to enable the gear 11b and the gear 1b to rotate the tray 1 about the shaft 1c until the center of the disc recess 1a in which a selected one of the discs 5 is mounted is brought into alignment with the playback position 12a, whereupon the drive motor 11a is de-energized. The pickup 13 is lifted by the pickup lifting/lowering mechanism 10, and the turntable 13a and a magnet clamp 12 jointly clamp the selected disc 5 therebetween.
The disc 5 is then rotated about its own axis by the turntable 13a, and the optical system 13b, while under focusing and tracking control, reproduces a recorded signal from the disc 5.
While the disc 5 is being played back, the tray 1 is positioned in the housing 3. Therefore, it is impossible to change the other discs during the disc playback. As long as the tray 1 is positioned inside the housing 3, it is impossible to confirm the labels of the discs 5 irrespective of whether a disc 5 is being played or not. For confirming the discs 5, it is necessary to withdraw the tray 1 out of the housing 3 and rotate the tray 1 to move the discs 5 successively into an outer exposed position where the user can recognize the information printed on the labels of the discs 5. When the discs are to be mounted on and removed from the tray 1, the tray 1 has to be ejected from the housing 3 and rotated so that the discs can be loaded or unloaded one by one.